Spotlight
A lighting rig is a large bank of lights that creates lighting effects at concerts and sporting events. A company makes rigs with lights arranged in polygonal patterns. For example, a triangular rig may have 1, 3, 6, 10, or 15 lights, depending on its size. Thats all I have /:

T(n)=n^2+n/2
Replace each n above with n+1 to obtain the value of T(n+1)
T(n+1)=(n+1)^2+(n+1)/2
f(n)=T(n)*T(n+1)=(n^2+n/2)((n+1)^2+(n+1)/2)
Expand the RHS above and simplify to obtain the reduced form of f(n)